Decay of hollow atoms in Ne¹⁰⁺-C₆₀ collisions

We have studied the decay of hollow atoms formed in Ne¹⁰⁺-C₆₀ collisions at low energy (E=100 keV). The decay products of hollow atoms, i.e., the scattered projectiles and the number of ejected electrons from autoionization cascades, have been measured. The projectile energy loss has been analyzed as a function of the final charge state, in order to differentiate collisions at large distance, near the C₆₀ through the electronic clouds and inside the C₆₀ cage. For scattered projectiles Ne⁸⁺ where two electrons are stabilized (s=2), up to 16 ejected electrons have been observed, and lower energy loss compared to projectiles with more stabilized electrons (s>2) has been measured. These results are interpreted by the formation and relaxation of completely neutralized compact hollow atoms passing very close to the C₆₀ molecule (into the electron clouds). The observed large number of ejected electrons is explained by a direct filling of the N shell during the interaction time and a fast decay via quasicomplete autoionization cascades.